Transparent Proxying

    The general network structure that will be used in this documentation is shown in the following figure.

    ATS basic traffic flow of Transparent Proxy

    There must be a gateway device through which all network traffic passes from the client to the Internet (or external cloud). The gateway is responsible for effectively splicing ATS in to selected streams of that traffic. Each traffic stream is split in two, with ATS terminating both sides. That is, stream green-1, red-2, is split in to the green connection and the red connection. Note that ATS may or may not be on the gateway system, the redirected traffic can flow over other network infrastructure.

    Because ATS uses two connections, transparency can be set independently on the client and origin server (Internet / external cloud) side. We will define what is generally called “transparent proxy” as two aspects, inbound transparency and outbound transparency.

    Inbound transparency is a proxy that is transparent to connections that are inbound to the proxy, i.e. a connection initiated by a client which connects to the proxy (green-1). Similarly, outbound transparency is a proxy that is transparent to connections that are outbound from the proxy, i.e. a connection initiated by the proxy to an origin server (red-2).

    In most situations these two types of transparency are combined, but that is not required. Traffic Server supports transparency independently on the two sides.

    Important

    • TPROXY

    • POSIX capabilities

    In addition the specialized routing will require using and in some cases ebtables.

    Standard build procedures should work for transparency support but if not consult these more detailed instructions.

    Transparency is configured per server port, not globally. This is done via the configuration values . In addition, proxy.config.reverse_proxy.enabled must be enabled if the client side is transparent. That should be fixed in a future patch.

    In the first case use the attribute character (replacing the default ‘X’)

    Attribute Transparency Style Reverse Proxy

    >

    Inbound (client) transparency: enabled

    Outbound (origin server) transparency: either

    In the outbound transparent case clients must connect directly to ATS either through an explicit proxy mechanism or by advertising the IP address of the ATS server via DNS as the origin server address.

    Some tested scenarios –